The present disclosure is related to frequency changer circuits, for example, in a mobile communications device. The mobile communications device may include receive and transmit channels for mobile communications, for example, of voice and/or data in a mobile phone, and/or the mobile communications device may include GPS circuitry.
Mobile communications devices typically include transmitters and receivers. The transmitter generates a signal, for example, carried at baseband, and modulates that signal so that the signal can be transmitted at a higher radio frequency (RF) carrier frequency. For example, the RF carrier frequency of a transmit signal of a CDMA mobile phone may be at 835 MHz. A receiver receives a receive signal at an RF carrier frequency unique to the receive signal (e.g., at 880 MHz for CDMA), and modulates that signal by changing its carrier frequency to a lower frequency, e.g., to an intermediate (IF) frequency and/or to baseband. A mobile communications device may further include a global positioning system (GPS) receiver to receive GPS signals. The GPS receiver receives a GPS signal at an RF carrier frequency unique to the GPS signal, and changes the carrier frequency of the received GPS signal to a lower frequency, for example, to an IF frequency and/or to baseband.